This invention relates generally to a fuel injection apparatus, and specifically to fuel injection nozzles for use in an internal combustion engine.
A number of different types of fuel injectors are known in the art, and these devices generally use conventional fuel injection nozzles to introduce droplets of fuel into the combustion chamber of an engine, thus increasing the surface area of fuel available for reaction. Increasing the surface area of the fuel affords a more efficient combustion reaction in internal combustion engines.
A number of improvements have been made to the fuel injection process in internal combustion engines that allow such fuel injection devices to function more efficiently within the fuel injection system. For example, U.S. Pat. No. 5,020,498 describes a fuel injection apparatus designed to provide a direct connection to supply lines or pressure lines to avoid pressure waves that may arise in the supply line network, which can have a disruptive effect on the injection quantity. In this device, a direct line connection with fuel supply lines is avoided during the injection event, the result being that pressure waves that develop in the lines cannot affect the injection event. In another example, British patent No. 2,099,078A describes the use of a compound rotary valve to control the timing and duration of opening the intensifier cavity to either the high pressure actuation fluid or to the low pressure fuel drain. In a further example, U.S. Pat. No. 5,697,341 describes fuel injectors that are hydraulically actuated, with fuel pressurized by a plunger driven by an intensifier piston. Fuel in the hydraulically actuated devices can be metered into the injector either by biasing the plunger with a return spring, or by pressurizing the fuel to hydraulically push the plunger in a retracting direction between injection events.
Although the quantity and quality of injection in the fuel injection apparatus have been improved by altering the method and route of fuel delivery to the device, these improvements have not addressed the efficiency limitations of the nozzle mechanism per se. Each of the above-described systems, which have enhanced delivery of fuel, use a conventional VOP type of needle check and nozzle. Examples of conventional nozzles can be found in: U.S. Pat. Nos. 4,662,338; 4,603,671; and 4,363,446. Such methods of delivery through conventional nozzles have technological limitations, such as limits on the minimum size of the expelled fuel droplets, the amount of energy transfer necessary to produce the fuel droplets, and clogging of the nozzle due to build up of residue left by the fuel composition.
There is a need in the art for a method of more efficient injection of fuel into an internal combustion engine or other similar device, e.g. by decreasing the size of the fuel droplet thus increasing the surface area available for the combustion reaction. Accordingly, there is a need in the art for a nozzle to improve the efficiency of fuel delivery in a fuel injection system.
A fuel injection nozzle for use in a fuel injection apparatus of an internal combustion engine is provided. The fuel injection nozzle of the present invention has a unique fuel delivery system comprised of a pressure chamber and a fuel source. Atomized fuel particles within a desired size range (e.g., 5 micron to about 500 microns, and preferably between 10 and 100 microns) are produced from a liquid fuel formulation provided via a fuel supply opening. The fuel may be provided in any desired manner, e.g., forced through a channel of a feeding needle and expelled out of an exit opening of the needle. Simultaneously, a second fluid contained in a pressure chamber which surrounds at least the area where the formulation is provided, e.g., surrounds the exit opening of the needle, is forced out of an opening positioned in front of the flow path of the provided fuel, e.g. in front of the fuel expelled from the feeding needle. Various parameters are adjusted to obtain a stable fuel-fluid interface and a stable capillary microjet of the fuel, which allows formation of atomized fuel particles on exiting the opening of the pressurized chamber.
Fuel injectors of the invention have three significant advantages over prior injectors. First, fuel never contacts the periphery of the exit orifice from which it is emitted because the fuel stream is surrounded by a gas (e.g. air) which flows into the exit orifice. Thus, clogging of the orifice is eliminated or substantially reduced. Second, the fuel exits the orifice and forms very small particles which are substantially uniform in size, thereby allowing faster and more controlled combustion of the fuel. Third, by using the methods described herein, the amount of energy needed to produce aerosolized particles of fuel is substantially less than that required by other methods.
An object of the invention is to provide a device for efficient delivery of a fuel to a combustion chamber of an internal combustion engine.
Another object is to provide a method of creating an fuel aerosol of consistent particle size, which increases the surface area available for a combustion reaction.
A feature of the invention is that the diameter of the opening from which fluid is expelled, the diameter of the opening from which fluid is expelled and the distance between these two openings is adjustable and is adjusted to obtain a stable fuel-fluid interface which results in a stable capillary microjet being formed by the fuel expelled, which microjet is focused on an exit opening by the flow of surrounding fluid (e.g. air).
An advantage of the invention is that it consistently produces fuel particles within a desired particle diameter range.
Another advantage of the invention is that the method of aerosolization of the fuel discourages agglomeration of the particles upon entering the combustion chamber.
An advantage of the invention is that fuel injection using the device of the invention is energy efficient.
Another advantage is that the structure of the device and its use are simple.
Another advantage is that clogging of the exit opening of the pressure chamber is substantially eliminated because the fuel is kept out of contact with the surface of the exit opening by a surrounding focused funnel of fluid, which flows out of the pressure chamber exit opening.
Yet another advantage is that particles produced are substantially smaller in size than would be expected based on the diameter of the exit opening of the pressure chamber due to focusing the flow of the fuel with the flow of surrounding fluid.
An aspect of the invention is a fuel injection nozzle that is one element of a fuel injection device and system.
Another aspect of the invention is a device which provides for the rapid engagement and disengagement of the aerosolization process.
These and other aspects, objects, features and advantages will become apparent to those skilled in the art upon reading this disclosure in combination with the figures provided.